Sulfonamido derivatives inhibiting the aldose reductase enzyme system and pharmaceutical compositions containing them

ABSTRACT

The xanthosulfonamido and benzensulfonamido derivatives corresponding to the formula: ##STR1## wherein x represents hydrogen, alkyl, alkoxy or halogen, Y represents an alkyl, alkoxy or halogen and Z represents the group ##STR2## or Y and Z taken together form the group: ##STR3## wherein R 1  in turn is a group selected among electron attracting groups, halogens and the group: ##STR4## itself, possess activity in inhibiting the aldose-reductase enzyme system and are thus useful in the treatment of the complications, at the eye and peripheral neuropathy levels, as induced by diabetes.

The present invention relates to novel sulfonamido derivatives havingthe property of inhibiting the aldose reductase enzyme system,particularly, xanthosulfonamido and benzensulfonamido derivatives.

In recent years a number of studies has been carried out with respect tothe diabetes and mainly to the complications induced by this disease,such as cataract, retinitis and peripheral neuropathy.

According to these studies, particularly, the genesis of thosecomplications seems to be attributed to the enzyme catalyzing theconversion of glucose into sorbitol and of galactose into dulcitol.

As a matter of fact, under pathological conditions, the excess ofglucose present in the diabetic patient causes an accumulation ofintracellular sorbitol to occur with relevant hyperosmotic effect andinflow of the fluids within the cell.

This picture is the pathogenetic base of the above mentionedcomplication of the diabetes, mainly of those relating to eyes and tothe peripheral neuropathy.

Referring to this pathogenetic origin substances have investigatedcapable of inhibiting the aldose reductase enzyme.

For information purpose the following papers published in the literaturecan be cited:

N. Canal and G. Comi, Aldose Reductase Inhibitors: Pharmacological dataand therapeutic perspectives, TIPS- Aug. 1985, pag. 328;

Cristopher A. Lipinski et al., Aldose Reductase Inhibitors as a NewApproach to the Treatment of Diabetic Complications, Ann. Rep. Med.Chem., 19, 169; 1984;

Richard Poulson et al, Inhibition of Aldose Reductase in Five Tissues ofthe Streptozotocin Diabetic Rat, Biochem. Pharmacol. 32, 1495, 1983;

D. Dvornik et al, Polyol Accumulation in Galactosemic and Diabetic Rats:Control by an Aldose reductase Inhibitor, Science, 182, 1146, 1973;

N. Simard-Duquesne et al., Prevention of Cataract Development inSeverely Galactosemic Rats by the Aldose Reductase Inhibitor, Tolrestat(42048), Pr. Soc. Exp. Biol. Med., 178, 599, 1985;

Sorbinil, Aldose Reductase Inhibitor, Drug of the Future, 11 (4), 345,1986.

From this literature it is evident that the relationship between thecomplications of the diabetes and aldose reductase enzyme system becamemore and more precise and that the inhibition of the latter system isconsidered a main route for the therapeutical treatment of thesecomplications.

The subject of the present invention are novel compounds of the class ofthe sulfonamido derivatives, particularly xanthosulfonamido derivativesand benzensulfonamido derivatives, showing a remarkable inhibitingactivity towards the aldose reductase enzyme system, whereby they appearas useful therapeutical agents in the treatment of the above mentioneddiabetes complications.

The novel derivatives according to the present invention have thefollowing general formula: ##STR5## wherein X and Y represents an alkyl,alkoxy or halogen and Z represents the group ##STR6## or Y and Z takentogether form the group: ##STR7## wherein R₁ in turn is a group selectedamong the electronattracting groups, halogens and the group ##STR8##itself.

As the preferred examples of electronattracting groups there can becited --COOH, --CO--CH₂ --R₂, CF₃ (wherein R₂ is an alkyl radical),whereas as regards the halogens, the selection can take place amongfluorine, chlorine and bromine.

The process for the preparation of the compounds of the presentinvention contemplates in a first step the preparation of thesulfo-chloride, having the desired substituents, and, in a second step,the reaction of the sulfo-chloride with N-methylglycine.

The following examples illustrate, without limiting purpose, thepreparation of the compounds of the present invention.

EXAMPLE 1

(a) 80 g (0.347 moles) of 2-chloroxanthone (DHAR, J. Chem. Soc. 117,1068) are suspended in 210 ml of chlorosulfonic acid (368.1 g; 3.16moles) in a 500 ml one neck flask provided with refluxing coolant andcalcium chloride valve. The mixture is slowly heated in an oil bath upto 120° C. under magnetic stirring. It is maintained at 120°-130° C.until the gas development ceases (2-3 h). The cool reaction mixture iscarefully dropwise added to a becker containing ground ice undermechanical stirring. A heavy crystalline product is separated which isfiltered on Buchner and washed with iced H₂ O. It is dried in air. Thereare obtained 112 g (98%) of raw 2-(chlorosulfonyl-7-chloroxanthone.After TLC monitoring (silica gel F₂₄₅ ; toluene, acetic acid 14:1,visualizer UV) the product is used as such for the next reaction.

(b) The above raw sulfochloride (112 g, 0.340 moles) is suspended in anN-methylglycine solution (151.3 g; 1.7 moles) in 1N KOH (1.7 liters).The suspension is slowly heated with a water bath under magneticstirring. At about 70° C. all the solid goes into solution leaving onlya slight cloudyness. The hot solution is filtered on paper and slowlydropwise added to 5N HCl under mechanical stirring.

A white crystalline solid is thus separated. The product is cooled understirring. The raw product is filtered on Buchner, washed with H₂ O anddried. After crystallization from acetic acid there are obtained 94 g(72.4%) of 7-chloro-2-N-methyl-N-carboxymethyl)sulfamoylxanthone, m.p.246°-248° C. TLC: one spot (silica gel F₂₅₄ ; toluene, dioxane, formicacid 8:3:1).

NMR (60 MHZ; solvent Polysol; δTMS=O) δ2.95, S, 3H, ##STR9## 4.05, S,2H, ##STR10## 7.57 - 8, 70, m, 6H aromatics.

Analysis for C₁₆ H₁₂ Cl N O₆ S: M.P. 381.5.

    ______________________________________                                               C       H      N         Cl   S                                        ______________________________________                                        Calc. %  50.32     3.14   3.66    9.30 8.38                                   Found %  50.62     3.09   3.57    9.63 8.25                                   ______________________________________                                    

EXAMPLE 2

Starting from 2-fluoroxanthone (F. L. Allen and Coll., Tetrahedron 6,315, 1959) and proceeding as described in example 1, there is obtainedwith a total yield of 75% the7-fluoro-2-(N-methyl-N-carboxymethyl)sulfamoylxanthone. TLC: one spot.

m.p. 233.5°-235° C. (acetic acid).

NMR: δ3.95, S, 3H, ##STR11## 4.05, 2H, ##STR12## 7.6-8.7, m, 6Haromatics.

Analysis for C₁₆ H₁₂ FNO₆ S: M.P. 365.

    ______________________________________                                                  C    H          N      S                                            ______________________________________                                        Calc. %     52.60  3.28       3.83 8.76                                       Found %     52.45  3.21       3.75 8.70                                       ______________________________________                                    

EXAMPLE 3

11.8 g (30 mmoles) of xanthone-2,7-disulfochloride (H. Ulrich, U.S. Pat.No. 3,714,194 (1973); C.A. 78, 136074 U) are added to a solution ofmethyl-glycine (26.7 g; 300 mmoles) in 150 ml of 2N NaOH, under magneticstirring. The suspended solid is quickly dissolved. After storage forone night, the solution is filtered on paper and dropwise added to 5NHCl under stirring. A white microcrystalline product is separated; thesuspension is then centrifugated at 3000 rpm for 10-15 minutes. Themother solution is removed by decantation and the solid is washed withH₂ O still by centrifugation.

The product is taken with isopropanol and filtered on Buchner. The driedraw product is crystallized from DMF/isopropanol; there are thusobtained 7g (46.8%) of2,7-bis(N-methyl-N-carboxymethyl)sulfamoylxanthone having m.p.>250° C.TLC (silica gel F 254; n-butanol, H₂ O acetic acid 4:1:2 UV detector):one spot.

NMR δ2.95, s, 6H, ##STR13## 4.08, 4H, 7.7-8.8, m, 6H aromatics.

Analysis for C₁₉ H₁₈ N₂ O₁₀ S₂ M.P. 498 (neutralization equivalentweight 498).

    ______________________________________                                                  C    H          N      S                                            ______________________________________                                        Calc. %     45.78  3.61       5.62 12.85                                      Found %     45.60  3.51       5.45 12.80                                      ______________________________________                                    

EXAMPLE 4

42 g (0.138 moles) of 4,6-dimethylbenzen-1,3-disulfochloride (Pollack,Lusting, Annalen, 433, 193) are added in portions under magneticstirring to a solution of N-methylglycine (50 g; 0.560 moles) in 420 mlof 2N, NaOH, externally cooling at 0°-5° C.

The solid is slowly dissolved; after 12 hours at room temperature thesolution is filtered on paper and dropwise added to iced 5N HCl understirring. A white product is separated which is filtered on Buchner andwashed with H₂ O.

It is crystallized from ethanol/H₂ O giving 41g (73.2%) of4,6-dimethyl-1,3-bis (N-methyl-N-caboxymethl) sulfamoylbenzene, m.p.189°-190° C. TLC (toluene, dioxane, formic acid, 5:5:1): one spot (UV).

Analysis for C₁₄ H₂₀ N₂ O₈ S₂, M.P. 408 (neutralization equimolarweight=408).

    ______________________________________                                                  C    H          N      S                                            ______________________________________                                        Calc. %     41.17  4.90       6.86 15.68                                      Found %     41.05  4.85       6.70 15.55                                      ______________________________________                                    

The compounds of the present invention have been subjected topharmacological and toxicity tests with the hereinafter statedconditions.

For sake of semplicity the tested compounds are indicated byabbreviations in the following manner:

Compound of the example 4: ARI 1

Compound of the example 1: ARI 6

Compound of the example 2: ARI 8

Compound of the example 3: ARI 9

The toxicity tests after only one administration have been carried outon two animal species (mice and rats), using two administration routes(os, iv).

(a) Acute toxicity: mice

For these tests Swiss mice have been used, of both sexes, having averageweight 20 g, fasted after 18 hours and administered with water adlibitum. The animals were maintained under standard environmentconditions (temperature: 20°-22° C. and moisture 50%).

The compounds have been administered by gastric probe, suspended inMethocell or by injection (iv) dissolved in physiological solution withthe addition of sodium bicarbonate.

The animals have been kept under observation for 15 days.

The controls have been carried out several times in the first days andtwice a day in the next days. In the table 1 the conditions used and theresults obtained are reported.

(b) Acute toxicity: rat

Wistar rats, of both sexes have been used of average weight of 120 g,fasted after 18 hours and with water at libitum. The conditions ofstalling and the administration ways were the same as those reported inthe preceeding paragraph (acute toxicity: mouse).

In the table II the obtained results are reported.

                  TABLE 1                                                         ______________________________________                                                       Dose and                                                                      admini-   Admini-                                                                              N. of ani-                                                   stration  stration                                                                             mal used per                                                                           %                                    Species                                                                              Drug    route     volume group    Death                                ______________________________________                                               ARI 1   5000      20 ml/kg                                                                             5 ♂ 0+ 5 ♀                                       mg/kg/os                                                              ARI 8   5000             5 ♂ +  5 ♀                                                                  10                                                 mg/kg/os                                                       MOUSE                                                                         (Swiss)                                                                              ARI 1   500       20 ml/kg                                                                             5 ♂ 0+ 5 ♀                                       mg/kg/iv                                                              ARI 8   400              5 ♂ 0+ 5 ♀                                       mg/kg/iv                                                       ______________________________________                                    

                  TABLE 2                                                         ______________________________________                                                       Dose and                                                                      admini-   Admini-                                                                              N. of ani-                                                   stration  stration                                                                             mal used per                                                                           %                                    Species                                                                              Drug    route     volume group    Death                                ______________________________________                                               ARI 1   5000      20 ml/kg                                                                             5 ♂ 0+ 5 ♀                                       mg/kg/os                                                              ARI 8   5000      20 ml/kg                                                                             5 ♂  305 ♀                                       mg/kg/os                                                       RAT                                                                           (Wistar)                                                                             ARI 1   500       20 ml/kg                                                                             5 ♂ 0+ 5 ♀                                       mg/kg/iv                                                              ARI 8   500       20 ml/kg                                                                             5 ♂  405 ♀                                       mg/kg/iv                                                              ARI 8   400       20 ml/kg                                                                             5 ♂ 0+ 5 ♀                        ______________________________________                                    

TOXICOLOGY OF THE COMPOUND ARI 6 (Example 1)

    ______________________________________                                        1. Acute toxicity in the rat ip                                                                        1000 mg/kg                                           2. Acute toxicity in the rat per os                                                                    1000 mg/kg                                           3. Acute toxicity in the mouse per os                                                                  1000 mg/kg                                           4. Acute toxicity in the mouse ip                                                                      1000 mg/kg                                           ______________________________________                                    

Toxicity per oral administration repeated in the rat (30 days) -Testprotocol:

    ______________________________________                                        Compound     Doses mg/kg/die                                                  ______________________________________                                        Controls     --                                                               ARI 6        100                                                              ARI 6        200                                                              ARI 6        300                                                              ______________________________________                                    

Results:

No death

Behaviour and general status (no variation with respect to the controlgroup).

Biochemical and hematological parameters (no significant variation withrespect to the controls).

Microscope and hystomorphological examination: no alteration.

"In vitro" pharmacological tests.

"In vitro" tests have been carried out to evaluate the inhibition of thealdose reductase activity, prepared from the extract of bovinecrystalline lenses.

Preparation of the raw extracts.

4 bovine crystalline lenses (8 g) are homogenized by means of Potter inice bath with 40 ml of 50 mM phosphate buffer, pH 6.8, containing2-mercaptoethanol pH (5 nM). After centrifugation (12.000×g -20 min-4°C.) the supernatent is brought to 40% saturation with an ammoniumsulphate and centrifugated again (14.000×g). The supernatent is thenbrought to the 80% saturation (NH₄)₂ SO₄) and, after centrifugation for20 minutes and at 14.000×g, the sedimented matter is recovered andsuspended in 7 ml of phosphate buffer. The enzymatic preparation isdialyzed by ultrafiltration with AMICON ultrafiltration cell.

Dosage of the enzymatic activity

400 μl of phosphate buffer 0.25% pH 6.8 are supplemented with 200 μl ofNADPH solution (final concentration 100 μM), 170 μl of ammonium sulphatesolution (final concentration 0.4M), 100 μl of glyceraldehyde (5mM), 40μl of the preparation of the enzymatic extract and phosphate buffer orportions of the several compounds to be tested up to the final volume of1070 μl.

The reaction is carried out at 37° C., it starting with the addition ofthe enzyme and the diminution of optical density (D.O.) at 340 nM ismonitored by DU6 Beckman spectro photometer programmed for the directcalculation of the reaction rate (ΔE/min.).

The reference cuvette contains all the several substances apart from thesubstrate.

                  TABLE 3                                                         ______________________________________                                        IC.sub.50 (M)* values of the several compound on the aldose reductase         activity of raw extracts originating from bovine crystalline lens.            Compounds     IC.sub.50                                                       ______________________________________                                        ARI 1         3.6 · 10.sup.-6 M                                      ARI 5         1.4 · 10.sup.-6 M                                      ARI 6         9.2 · 10.sup.-6 M                                      ARI 8         1.0 · 10.sup.-6 M                                      ARI 9         1.0 · 10.sup.-6 M                                      SORBINIL      2.0 · 10.sup.-6 M                                      ______________________________________                                         *IC = 50 = concentration given in moles capable of inhibiting by 50% the      enzymatic activity.                                                      

The obtained results shown the certain inhibiting action of thecompounds of the invention of the aldose reductase activity.

The compounds ARI 8 and ARI 9, for this experimental model show higheractivity, with respect to the of sorbinil and of ARI 1.

"In vivo" pharmacological tests.

With the compound bearing the abbreviation ARI 6 the following testshave been carried out in the rat and in the rabbit.

Action on the appearance of the galactosemic cataract (rat)

Action on the appearance of the diabetic cataract (rat).

Results

In table 4 the experimental results obtained in the rat are reported. Itcan be pointed out that the appearance of the lenticular cloudiness inthe control animals developed in 20 days on average, whereas thetreatment with the doses of 5 mg/kg has shown a delay of about 20 daysfor the appearance of the cataract.

A more intense effect took place with the higher doses. The table 5shows the effect of the dose of 25 mg/kg on the appearance of thediabetic cataract. In this experimental model too the appearance of thecataract has been observed with a delay of about 30 days with respect tothe controls.

                  TABLE 4                                                         ______________________________________                                        Effects of the administration of ARI-6 (5 and 25 mg/kg/die, os)               on the appearance of the galactosemic cataract in the rat.                    Days from the be-      ARI 6      ARI 6                                       ginning of the                                                                             PLACEBO   5 mg/kg/die                                                                              25 mg/kg/die                                diet         (20)      (20)       (20)                                        ______________________________________                                        5            0.0       0.0        0.0                                         10           10.0      0.0        0.0                                         15           50.0      0.0        0.0                                         20           100.0     0.0        0.0                                         25           100.0     15.0       0.0                                         30           100.0     20.0       0.0                                         35           100.0     40.0       0.0                                         40           100.0     100.0      15.0                                        45           100.0     100.0      25.0                                        50           100.0     100.0      100.0                                       ______________________________________                                         The values are not expressed as a percentage. In the brackets the number      of animals for each group is indicated.                                       The diet contains Dgalactose 50%.                                        

                  TABLE 5                                                         ______________________________________                                        Effects of the administration of ARI 6 (25 mg/kg/die, per os)                 on the apperance of the diabetic cataract in the rat.                                                     ARI 6                                             Days from the administration                                                                     Placebo  25 mg/kg/die                                      of streptozotocine (10)     (10)                                              ______________________________________                                         5                  0.0     0.0                                               10                  10.0    0.0                                               15                  50.0    0.0                                               20                 100.0    0.0                                               25                 100.0    0.0                                               30                 100.0    0.0                                               35                 100.0    0.0                                               40                 100.0    20.0                                              45                 100.0    30.0                                              50                 100.0    100.0                                             ______________________________________                                         The values are expressed as percentages. Within brackets there are            indicated the animals for each group.                                    

In tables 6 and 7 corresponding to the tables 4 and 5, the valuesobtained with the compound ARI-1 are reported.

                  TABLE 6                                                         ______________________________________                                        Effects of the administration of ARI-1 (5 and 25 mg/kg/die, os)               on the appearance of the galactosemic cataract in the rat.                    Days from           ARI 1        ARI 1                                        the beginn-                                                                            PLACEBO    5 mg/kg/die  25 mg/kg/die                                 ing of the diet                                                                        (20)       (20)         (20)                                         ______________________________________                                        5         0/20 (0.0)                                                                              0/20    (0.0)  0/20  (0.0)                                10        8/20 (40.0)                                                                             0/20    (0.0)* 0/20  (0.0)*                               15       10/20 (50.0)                                                                             0/20    (0.0)* 0/20  (0.0)*                               20       20/20 (100.0)                                                                            0/20    (0.0)* 0/20  (0.0)*                               25       20/20 (100.0)                                                                            3/20    (15.0)*                                                                              0/20  (0.0)*                               30       20/20 (100.0)                                                                            4/20    (20.0)*                                                                              0/20  (0.0)*                               35       20/20 (100.0)                                                                            8/20    (40.0)*                                                                              0/20  (0.0)*                               40       20/20 (100.0)                                                                            8/20    (100.0)*                                                                             3/20  (15.0*)                              45       20/20 (100.0)                                                                            20/20   (100.0)*                                                                             5/20  (25.0*)                              50       20/20 (100.0)                                                                            20/20   (100.0)                                                                              20/20 (100.0)                              ______________________________________                                         The values represent the number of eyes with cataract on the total number     of observed eyes. The percentage values are put between brackets.             *Significant difference with respect to the controls (p < 0.05, Fischer       Test).                                                                   

                  TABLE 7                                                         ______________________________________                                        Effects of the administration of ARI-1 (25 mg/kg/die, per os)                 on the appearance of the diabetic cataract in the rat.                        Days from the strep-        ARI 1                                             tozotocine administration                                                                     PLACEBO     25 mg/kg/die                                      ______________________________________                                         5              0/20    (0.0)   0/20  (0.0)                                   10              8/20    (40.0)  0/20  (0.0)*                                  15              10/20   (50.0)  0/20  (0.0)*                                  20              20/20   (100.0) 0/20  (0.0)*                                  25              20/20   (100.0) 0/20  (0.0)*                                  30              20/20   (100.0) 0/20  (0.0)*                                  35              20/20   (100.0) 0/20  (0.0)*                                  40              20/20   (100.0) 4/20  (20.0)*                                 45              20/20   (100.0) 6/20  (30.0)*                                 50              20/20   (100.0) 20/20 (100.0)*                                ______________________________________                                         The values represent the number of eyes with cataract with respect to the     total number of observed eyes. The percentage values are put in brackets.     *Significant difference with respect to the controls. (p < 0.05, Fischer      Test).                                                                   

The pharmaceutical compositions according to the invention, namelyincluding the novel sulfonamido derivatives as the active ingredient,and useful for the prevention and/or therapy of retinic damages(cataract, retinopathy etc.) and of peripheral neuropathies in diabeticpatients. The pharmaceutical compositions of the invention are in formof a tablets or capsules, containing the standard vehicles andexcipients, besides the active compounds, and prepared according to thewell known pharmaceutical technologies. The daily posology foreseen forthe compositions of the present is of 50 to 200 mg/day, depending on theseriousness of the disease.

Consequently the tablets or capsules shall contain from 5 to 200 mg ofactive compound. Depending on the solubility in water of the activecompounds also solutions for parenteral administration are provided.

What is claimed is:
 1. A sulfonamido derivative having the generalformula: ##STR14## wherein X represents hydrogen, alkyl, alkoxy orhalogen and Y and Z taken together form the group: ##STR15## wherein R₁is a halogen, ##STR16## --COOH, --CO--CH₂ --R₂ (where R₂ is an alkylradical) or CF₃.
 2. The sulfonamido derivative according to claim 1wherein when R₁ is a halogen, said halogen is selected from the groupconsisting of fluorine, chlorine and bromine.
 3. The compound7-chloro-2-(N-methyl-N-carboxymethyl)-sulfamoylxanthone.
 4. The compound7-fluoro-2-(N-methyl-N-carboxymethyl)-sulfamoylxanthone.
 5. The compound2,7-bis(N-methyl-N-carboxymethyl)-sulfamoylxanthone.
 6. A pharmaceuticalcomposition suitable for use in treating retinic damage in a diabeticpatient comprising as an active ingredient an amount of said sulfonamidoderivative according to claim 1 sufficient to inhibit retinic damage,together with a pharmaceutically acceptable carrier.
 7. A method oftreating retinic damage in a diabetic patient comprising administeringto said patient an amount of said sulfonamido derivative according toclaim 1 sufficient to inhibit said damage.